Our overall goal is to understand the mechanisms underlying the control of synthesis of different Hb in man. We have now succeeded in the development of simple but reliable microanalytical methods to determine the synthetic rates of Hb in culture and have obtained fundamental information on the biological properties of cells capable of "postnatal reactivation" of HbF synthesis. We propose to apply these techniques to study the specific aspects of the clinical, cellular and molecular mechanisms controlling Hb biosynthesis. The cells will be grown in methylcellulose clonal culture and Hb globin chains will be labeled with 14C-amino acid mixture, separated by isoelectric focusing and quantitated by autoradiography or fluorography techniques. We will examine factors such as pure erythropoietin, burst-promoting activity (BPA) and hormones on HbF biosynthesis in culture. We will also examine the effects of murine erythroleukemia cell inducers. Serial prospective examinations of normal subjects as well as patients with sickle cell anemia will be used to analyze genetic versus acquired factors affecting HbF biosynthetic capabilities of individuals. We will then characterize cellular controls of HbF synthesis in individual bursts. Finally, synthesis of variant gamma-chains will be studied.